Unforgivable Things
by 8.Years.Of.Silence
Summary: Season 6 AU - Cas shows up at the boys' motel after a bad hunt with some good news. And some not good news. What happens to an Angel when they're forced to make difficult choices to win a war and stave off the Apocalypse? Warnings: Dark themes, adult language. One-Shot. **App Users: Reviews contain SPOILERS**


**Warnings** : Adult language, dark themes and death ahead. Season 6 AU.

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 **Unforgivable Things**

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It was a wendigo. That's what kept them out hunting for half the night and into the early hours of the morning. The damn thing was just as supercharged and active as all the other monsters out there, freaking out because Mommy Dearest had decided to come home early.

That, plus the ridiculously long trip to the hospital to get some much needed medical attention to the two survivors – a couple who decided to go hiking out in Bumfuck Nowhere and get their asses kidnapped by the freak of the week who hung them up to dry in a cave for two days. Not to mention the highly-detailed escape plan executed to get out of the ER before anyone started asking too many questions.

Doctors were worse than cops. It was like they trained those guys to ask conflicting questions so you couldn't keep your lies straight.

Actually, scratch that. Nurses were worse than doctors. Especially the frumpy ones.

Dean let out a huff of air as he pulled the floppy motel key out of his back pocket. All he wanted to do was sleep and sleep and then maybe sleep some more after that. It had been one hell of a trying week – hell, it had been one hell of a trying month. In fact, pretty much since Sam came back into his life, it had been one hell of a trying everything.

Not that he wasn't ecstatic about having Sam back. He was a little on the fence there in the beginning when Sam wasn't Sam, but Robocop on steroids. Talk about a fried microchip. But his brother was once more the loveable, monster-killing giant with a conscience they all loved. And missed. Really, really missed.

The sheer relief he had felt when Sammy woke up that day at Bobby's and looked at him with…well, _human_ eyes, had been almost overwhelming. Heart breaking, practically. Not that he'd admit it. Winchester's didn't do hearts, unless it involved some silver bullets and a good old hunting knife.

He heard Sammy shift behind him, just as tired as he was, if not more (the kid had taken a pretty hard hit to the cave wall at one point). Shuffling the duffle over his shoulder and the bag of supplies in his arms, he fit the thin piece of plastic into the lock. He missed keys. He liked keys. The way they jingled in his pocket always reminded him of his baby and that always put a smile on his face.

As soon as the stupid little contraption on the door gave them the blinking green light, he flipped the handle and pushed the thing open with his shoulder. Dean didn't get two steps in before he dropped the bag in his arms and pulled his firearm. He heard Sammy immediately do the same on principle, though it didn't stop him from calling his name in confusion.

The lights were off in the motel room, as they'd left them, but Dean knew something wasn't right. Keeping one gun trained on anything that might move, he reached over and flipped the switch. He barely held back the string of cusses as the poor lighting cast shadows over a tan trench coat.

"Cas," Dean growled out in warning, tucking the gun into the back of his jeans. "What the hell, dude!"

"Dean." Sam's warning, a mixture of relief and worry and confusion, stopped the hunter mid-rant and he glanced at his brother. But Sammy's eyes were focused on Cas.

The angel was a mess. His clothes were rumpled and askew (well, more than usual, at least) and covered in dirt and smears of what Dean really hoped wasn't blood. At least not Cas' blood. Jimmy's skin was pale and gaunt, tinged grey in a way that didn't bode well at all for the poor bastard. And there were circles beneath his eyes that could give the dead a run for their money.

When he finally turned to face them, the angel's eyes were hooded, and his gaze flickered between the two without settling on either of them.

"Cas?" Something in Dean's chest told him he should go to the angel, make sure the guy was alright. It didn't look like Cas had much more in him to stand, let alone make it to a chair. But he didn't, because something in his stomach was screaming not too. It was something he could hardly put to words, let alone explain. But he was…afraid.

As a hunter, Dean's gut was something to be rivaled. It was never wrong and had kept him alive through more situations than could be counted. And right now, his stomach was curling in knots over the very idea of him or his brother getting any closer to the angel.

"Cas?" Dean repeated. Beside him, he could feel Sam tensing up and knew his brother was having the same strange feeling. Thoughts raced through his mind, trying to prepare for any possible situation. Hell, it might not even be Castiel standing in front of them, but some other dick angel who had managed to take his vessel.

Just as he was entertaining the idea of reaching for his gun once more, the angel's eyes landed on him. It was only a brief moment before they flickered to Sam and back to him. Telling him something.

Dean frowned, glancing to his brother uncertainly before looking back to Castiel. "Sammy," he called slowly, not completely sure this was the best course of action, but the one that Cas apparently desired.

His brother nodded, almost too quickly. "Uh, right, I'll just be…outside." He picked up the bag he'd dropped earlier and backed out of the door, closing it behind him but not before giving his brother a quick nudge. An _'I'll be right outside if you need me'_ sort of nudge. And Dean knew his brother wouldn't go far. They'd both felt that odd fear.

Were still feeling it, in fact.

"Cas, what's going on?" Dean didn't move from his place by the door and eyed the angel warily. Cas wasn't meeting his eye again. There was something…dark about the angel. Something he couldn't put words to, but it was like a cloud hanging around the guy.

There was a long bout of silence between them, to the point where Dean was just about ready to give up on getting an answer (which he'd be pissed about, since he just friggin' wanted to go to bed already), when Castiel turned towards the window, eyes daring around the room. The movement was jerky. Skittish. Like he was uncomfortable in his own skin.

Dean's hand twitched for his gun.

The angel seemed to pace for a moment without ever moving. Like he didn't quite know what to do with his body or where he wanted to be. He settled on a hunched, almost curled stance as he stared at the curtains, like he was seeing right through them to the parking lot beyond.

"The war is over."

Dean's eyes widened at that. Was that what this was all about? Castiel and his fellow angels had lost the war in Heaven and come to warn them. Sure, that would put any guy down in the dumps and slightly off kilter. Of course, that could also mean that their Cas was actually dead and this was some new angel ready to try and kill them.

At least it wasn't Raphael. He couldn't fit in Jimmy (and boy when he felt more comfortable, he would take a moment to laugh at that innuendo). That was some comforting information. Sort of.

"Did you…" Dean wasn't sure how to finish that sentence. Was it kind of harsh to assume Cas had lost and ask him outright?

"We won. Raphael is dead."

The silence that followed that sentence was like one he had never experienced. It was that last moment on a roller coaster, just after you've finished climbing the hill and you can see the fall in sight. When everyone gets quiet and has half a second to figure out which side of the fence they'll fall on; the irrational excitement that defies all primal instinct, or the logical fear drilled into you by years of evolution.

"That's….that's friggin' fantastic, man!" He tried for the excitement, hoping that building sensation in his stomach was wrong (the one that said that riding a car on a rickety set of rails 80 feet off the ground and 60 miles per hour was not a smart idea).

Cas spared him a long glance and Dean sucked in an icy breath. Those blue eyes, the ones he was pretty sure got Jimmy his wife, were black. Not demon black. But lightless. Evil. Wrong.

Dean fought every muscle in his body to keep himself from taking a step back.

"Yes," Cas continued after a moment. He listlessly shuffled about, checking the room once more with darting eyes. There was another moment of discontent as the angel shuffled from foot to foot and Dean tried very hard to stay still.

And then Cas's right arm twitched and suddenly there was a blade, an angel's blade, glinting in the dim, yellow light.

Dean's handgun was out before he could blink, half raised at the angel and cursing because he knew bullets weren't going to do crap to the guy. "Cas?" The warning, plus the weapon, were enough to halt the angel, who had started towards the hunter. Dark eyes drifted from the weapon to the man behind it.

"I'm not going to hurt you, Dean." His voice was rough with something Dean couldn't place. Derision? Annoyance? Pain?

He lowered the gun ever so slightly, but refused to put it away. "Then what's with the blade, buddy?"

Castiel looked down at the sleek silver gripped in his hand. Fingers slowly uncurled, as if he was discovering what he was holding for the first time. Blue eyes that weren't so blue anymore closed and he bowed his head.

Dean called his name, hand tightening on the grip of his gun, but Cas didn't respond. Finally, the angel straightened to his full height, even as his shoulders remained slumped. Like he just didn't have it in him anymore.

"The blade is for me, Dean."

The hunter lowered his gun out of sheer confusion, straightening as a frown came to his face. "For…you?" he repeated, eyes darting between the blade and the angel. "What the hell are you talking about?"

Castiel stepped towards him, cautious of the gun still gripped in the hunter's hand. Not that it could harm in the slightest, but his intention was not to frighten Dean, who seemed to be a skittish animal in his presence.

The angel raised his weapon, letting the weight of the hilt slip through his hand to spin and present the handle to Dean. Confused, the hunter took it with his free hand, eyeing the silver blade. It was heated from Castiel's touch, something that seemed weird to the hunter.

"And what am I supposed to do with this? I thought you said the war was over." Dean hoped this didn't mean all of Raphael's pissed off buddies were now gunning for him and Sam. He really didn't have time for both the pissy Mother of the Year and a bunch of sore losers.

"It is over, Dean. That is for me."

And suddenly the light bulb went off in Dean's head as he stood with Castiel in front of him, waiting, and his own arm stretched between the two of them, blade pointed practically at the angel's heart.

The sword clattered to the floor between them.

"What?" Dean yelled, somehow making the word sound like the foulest curse he'd ever uttered. He took a step back, several in fact, and shook his head. "No. No way. What the hell, man! I'm not killing you!"

Castiel retrieved the sword and once more held the handle out to him. "You're a hunter, Dean. And I have become a monster."

That stopped the older Winchester cold and he looked from the blade to the angel. "What?"

"I've become a monster. I know you can feel it. You are scared of me." Dark eyes flickered blue for just a moment as they fought to stay locked with Dean's. But whatever he saw in the hunter's gaze served as confirmation, and Cas looked away. Dean's chest tightened, not because it was true, but because Cas knew it. And it was hurting him.

"No, man," the hunter said softly, shoulders dropping. "I mean…sure, there's something off about you, but I'm not scared of you. You're my…friend."

"Lying is a sin, Dean." A corner of a smile teased at his stoic face before he sighed. The angel shuffled, body turned to the side and blade clenched in his hand. After a deep breath, he turned once more to the man he gave up everything for and held out the blade. "Look me in the eye and tell me that I'm not something that needs to be killed."

And Dean tried. He tried really, really hard, but no words would come out. Those pitch black eyes were devoid of any of the light the angel had once had and Dean knew, without a doubt, that this was no longer his friend standing in front of him. The last shreds of grace the angel desperately clung to would not pull him out of this abyss.

Castiel's eyes once more dropped. He had his answer. "I have done things – unforgivable things – to win this war. And I am Falling."

"You fell before," Dean rallied but there wasn't much strength in it. He knew this wasn't the same. He didn't know how, but this definitely wasn't like before.

"I was cut off, Dean. I rebelled and for that I was exiled, but not Fallen." Cas took a step towards him, backing him into the wall and invading his personal space. "I will not let myself become like Lucifer. I will not save this earth only to grow to despise it." Dean felt the metal press into his hand and he realized how cold it felt now. Deathly. "I need you to do this."

The hunter shook his head, but had no more refusals to give. Castiel's hands were wrapped around his on the blade and he knew he was going to do this, whether he wanted to or not. Everything he was – scarred and broken and dark - shouted at him to refuse, to throw the knife aside, to tell Cas to fuck off and how could he ask that of him! Yet his fingers tightened around the hilt and he knew he couldn't deny the damn angel a thing.

"Cas-"

"I do not regret the choices that led me here." The angel stared into his eyes and Dean searched, desperately, for anything that even resembled blue. For a moment, he thought he saw it again. "You and Sam have taught me freedom, and this is the price I agreed to pay for it. I would not give up that up. Not for anything."

Dean found himself nodding even as the angel took a step back and raised his arms to either side, giving the hunter free range of his body. The man didn't move, just stared at the angel. But a battle of wills and patience isn't easily won against a guy who doesn't know how to be impatient.

"Tell Sam I said goodbye."

"I'm sorry." Dean was moving before he even knew what he was doing; he wrapped his arm around Castiel's back, hand digging into the coat and pulling the angel into him. Their bodies met with force, trapping his arm between them. A weak gasp broke the silence and Dean dropped his head, cheek brushing Cas's. He repeated himself, whispering it against the angel's ear in a broken voice. "I'm so sorry."

"Don't be," came the soft reply. Hands slowly wrapped around him, gripping the back of his shirt. There was something harsh in his voice, a crackling of energy even as blue-white light began to seep out between their bodies. Castiel's eyes lit for a final time, chasing away the darkness as his body was consumed by the explosion of his grace.

A flash tore Dean away from the angel, shoving him back as light engulfed the room and he stumbled, covering his eyes.

When the blast finally faded and he stood, lowering his arm, there were tears streaking down his face. Castiel's body – Jimmy' body – lay in the middle of the motel room, clear blue eyes staring, unseeing, upwards, trench coat spread out around him, framed by a pair of beautiful blackened wings, scorched into the floor and across the beds.

Dean's knees gave and he hit the floor, blade still in hand even as the motel door slammed open and Sam ran in, ready to fight against the angel Dean had just killed.


End file.
